Electrical contacts are present in all avionics, military and aerospace equipment environment such as in helicopters, missiles and planes. Such equipment may have dozens or even hundreds or even thousands of electrical connections that must be made between electronic power supplies, sensors, activators, circuit boards, bus wiring, wiring harnesses, to provide the electrical pathways or highways needed to transport electricity in the form of control signals and power. The hardware reliability requirements for operating in an avionics environment are stringent as a failure can have catastrophic consequences. As such, the electrical components and circuitry, as well as the connectors and contacts therein employed to electrically connect these items, must work in a wide range and wide variety of environmental conditions such as mechanical, vibration, wide temperature ranges, humidity and corrosive elements, etc. For example, military standards (also known in the industry as mil specs) for aircraft avionics equipment require that contacts be able to mate and unmate a minimum of five hundred times without a failure during all anticipated environmental and mechanical conditions. In addition, the contact assemblies must be protected to withstand repeated handling without significant distortion or damage to the interconnecting parts which could lead to a lack of electrical continuity.
One example of a high-amperage power socket contact or terminal is illustrated in U.S. Pat. No. 5,376,012 "Power Port Terminal" to Clark which includes a contact socket receiving portion and an integral mounting portion. The socket includes a web with a plurality of beams thereon. Each of the beams has a curved surface with a bend, which beams cooperate to form an axially extending tubular socket region which accepts a pin terminal of any desired length. Disadvantageously, the beams are exposed and therefore subject to damage. Additionally, the beams of the socket contact are not protected from entry of an oversize male contact, which may bend the beams beyond their elastic limit thereby damage the connector so that it will not perform electrically.
Another example of a socket contact is illustrated in U.S. Pat. No. 4,906,212 entitled "Electrical Pin and Socket Connector" to Mixon, Jr. which includes a socket have a cylindrical mating portion defined by cantilever beams having one or more blades wherein one or more of the blades include a rearwardly extending free end. The pin includes a mating portion having a bullet nose at one end and a wire barrel at another end. This connector suffers from the same limitations as the Clark connector and therefore is an undesirable alternative in environments where high reliability is critical.
A prior art female contact which is used in non-critical and in non-aerospace applications is shown in FIG. 1 which contact includes a cylindrical member 10 having holes 12 and 14 in the ends thereof. A spring member 16 is inserted in one of the ends, the spring member tapering rearwardly into the hole 12. Accordingly, a male pin contact inserted into the cylindrical member 10 would be grasped by the spring member 16 relatively deeply within the hole 12 which is disadvantageous. The distance from the free end 15 of the socket to the point of engagement 17 with a male contact or pin is designated by the letter "l" in FIG. 1 (and in FIG. 2). The particular connector halves in which the male and female contacts are used (and the positioning of the connector halves on the equipment, e.g., trays and black boxes) may result in a lesser or greater penetration of the male pins into the socket body. Furthermore, there is no mechanical structure to ensure that the spring member 16 will remain in place and as such the spring may "walk out" of the hole during vibration or during mating and unmating cycles. Mil specs require that a spring member which provides the electrical continuity must be able to withstand the separation force during the unmating cycle (i.e., 500) without being dislodged under all anticipated environmental conditions including vibration. The arrangement of the spring 16 socket member 10 could be potentially hazardous if used in avionics environments where high reliability is a must for human safety.
Another example of a socket contact that is successfully manufactured and sold by the assignee of the present invention is shown in FIG. 2. This contact 20, sometimes referred to as a hooded socket contact, includes a tubular socket body 22 having a plurality of tines 24 for receiving a male contact or pin. A hood 26 is inserted over the tines 24 and rear portion of a contact to protect the tines from damage. The hood is generally made of stainless steel with a wall thickness of only 0.004 to 0.010" for economic and reliability reasons. The hood is press fit over the cylindrical shoulder portion 28 at the rear of the contact. This press fit arrangement, due to the hood's wall thickness, requires precision manufacturing. Improper sizing of the socket body shoulder may result in damage to the hood during the press fit operation or the hood may come loose during use. Plating of the contact may exacerbate the press fit step during manufacturing. Furthermore, a stainless steel hood may not be tolerated in certain applications where interference with magnetic fields is a problem. In summary, the manufacturing steps necessary to insure reliable performance of the hooded type contact shown in FIG. 2 may result in a fairly expensive contact when mass produced.
Accordingly, there is a need for an improved socket contact that is simple to manufacture yet reliable in performance and that can be made in mass quantities at relatively low cost.